1. Field of the Invention
This invention relates to scissor jacks for lifting vehicles and more particularly to a light weight, compact jack which is inexpensive to manufacture, easy to operate, less prone to squeaking and rattling when stored in a vehicle trunk, less prone to damage the finish of a car, greaseless, and meets other enhanced performance requirements.
2. Description of the Prior Art
The use of scissor jacks to lift a vehicle for changing its wheels, repairs or other needs is well known. Existing scissor jacks have evolved to consist of a combination of links, pins and a lead screw, all generally made from steel. Although these products have provided satisfactory service in the past when lifting load capacity was the only requirement, they do not meet the present requirements of light weight, low cost, small package, low effort in the use, and resistance to rattle/squeak noises. Vehicle manufacturers today need to provide the users with an ultra light weight jack with the required lift capacity and factors of safety. Also, the extreme shortage of space to store the jack in the trunk of the vehicle demands an efficient, compact package. From the vehicle user's point of view, the lowest possible effort needed to raise the vehicle and to handle the jack from storage is desirable. Vehicle owners also object to the squeaking and rattling of the jack in the trunk of the vehicle.
Some examples of prior art jacks include the jack disclosed in U.S. Pat. No. 4,025,054 to Yamazaki which is a pantographic jack having two pairs of arms which include gear teeth portions on the ends of the arms. The gear teeth portions are formed integrally with the arms and extend at a right angle therefrom. The arms in Yamazaki's jack are of U-shape configuration and the teeth on the gears are formed from the flanges of the U-shape arms.
Engels U.S. Pat. No. 4,802,653 discloses a scissor jack which is formed with a base and four channel shaped link members and a threaded shaft for raising and lowering the jack. Engels' invention relates to a quicker and easier way to assemble the jack due to the use of slots in the ends of the arms for receiving the rivets which hold the jack together.
Yamayuchi et al U.S. Pat. No. 4,848,733 discloses a vehicle jack assembly having a pantographic mechanism carrying a head bracket for engaging a lower surface portion of a vehicle body. The jack has upper arms and lower arms which are of channel shaped cross section and utilizes a screw shaft for raising and lowering the head bracket of the jack. Billingsley U.S. Pat. No. 1,376,507 discloses a four piece scissor jack wherein the four pieces are of similar construction and have toothed end portions for engaging one another. Billingsley's lead screw has a right hand thread on one end and a left hand thread on the other end.
Other discloses of interest are contained in Steppon U.S. Pat. No. 3,317,189; Kolodin U.S. Pat. No. 2,920,871; Curran U.S. Pat. No. 1,994,015; Larsen U.S. Pat. No. 1,736,202; and Peck U.S. Pat. No. 2,580,829.
Despite the efforts made by prior inventors, there continues to be a need for an ultra light weight jack with the required lift capability and factors of safety necessary for the user. There is also a need for such jack to be low cost and compact, as well as have a low required effort for use and be quiet when stored in the vehicle trunk.